Curtain sign (enhanced ptosis)

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The curtain sign (enhanced ptosis) is one of the many eye signs of myasthenia gravis. Hering’s law of reciprocal innervation states that the extraocular muscles receive equal bilateral innervation. In MG, extraocular involvement is variable and asymmetric leading to ptosis that is bilateral but often unequal. Both lids receive the same level of innervation and firing is maximal attempting to hold the lids open. The lid less involved by the disease process is open wider. Manually elevating the more ptotic lid sends a signal to the less ptotic lid that it can relax a bit and the ptosis increases.(1,2) The manual elevation of the more ptotic lid causes the level of firing to decrease and the previously less ptotic lid suddenly collapses (Video). Manually raising the more ptotic lid causes increased ptosis on the opposite side. For another example see http://journals.lww.com/continuum/pages/videogallery.aspx?videoId=113&autoPlay=true

Enhanced ptosis has also been reported in LEMS.

Video courtesy of Dr. Stephen Reich, Department of Neurology, University of Maryland

References

1. Gorelick PB, Rosenberg M, Pagano RJ. Enhanced ptosis in myasthenia gravis. Arch Neurol. 1981;38:531.

2. Campbell WW. Clinical signs in neurology : a compendium. Philadelphia: Wolters Kluwer Health, 2016.

3. Brazis PW. Enhanced ptosis in Lambert-Eaton myasthenic syndrome. J Neuroophthalmol. 1997;17:202-3.